Temperature control in oil fired central heat plants



Oct. 7, 1941. P. H ARTMANN-RHS 8, 5

TEMPERATURE CONTROL IN OIL FIRED CENTRAL HEAT PLANTS Filed May 29, 19372 Sheets-Sheet 1 F/ I 7 y 1/ 16 1 T HJ W9 V vs V Oct. 7, 1941. P.HARTMANN-RIIS 2,258,385

TEMPERATURE CONTROL IN OIL FIRED CENTRAL HEAT PLANTS Filed May 29, 19372 Sheets-Sheet 2 Patented Oct. 7, 1941 UNITED STATES PATENT OFFICE-TEMPERATURE CONTROL IN 01L FIRED CENTRAL HEAT PLANTS PotterHartmann-Rils. Ostre Alter, near Oslo,

, Norway Application n... 29, 1937, Serial No. 145,818

In Norway March 4, 1936 Claims. (Cl. 236*91) in the boiler, in order toavoid frequent extinc-,

tions and ignitions of the flame. and the waste of heat resultingtherefrom.

It has also been suggested to automatically regulate the boilertemperature in relation to the outsid temperature. Thus the use of acompound thermostat has been proposed, which is simultaneouslycontrolled by the pressure of a medium in a bulb arranged outsidethebuilding and a bulb in the boiler. However, such apparatus is notconsidered dependable in use.

Apparatw is also known having a special set of thermostatsi'or eachoutside temperature and the desired corresponding water temperature.Such apparatus, however, is complicated and expensive.

The object of the present invention is to provide an automaticelectrical system for controlling thetemperature of the boiler in apredetermined relation to the existing outside temperature. Theinvention also includes the control of the size of the flame in relationto the outside temperature'and the simultaneous use of these two controlmeans, in order to obtain smooth operation of thesystem with the bestpossible heat economy.

According to the invention a switch is arranged in the circuit of themotor, which drives the oil pump and the airblower oi theoil burner. Theswitch opens the circuit at a definite boiler temperature, which ispredetermined in. relation to an existing outside temperature, wherebythe motor stops and the flame is extinguished. This disconnection of themotor may be eflected by the closure of another circuit through acontact piece actuated by a temperature sensitive instrument, arrangedin the open air and another contact piece, t..e position of which isdetermined by the boiler temperature. By the closure of this circuit arelay may be actuated to disconnect the motor.

A further object of the invention is the provision of means for theautomatic control of the size of the flame in relation to the out-doortemperature. It is evident that a low out-door temperature calls for alarger flame than a higher temperature. In the last case the flame willbe frequently extinguished and ignited unless the size of the flame benot adequately conrolled.

According to the invention this may be accomplished by imparting to themotor, which drives the oil'pump and air, blower of oil burner, adefinite number of; revolutions in relation to the out-door temperature,whereby the size of the flame will be controlled.

This may be effected by placing resistances of definite sizes inrelation tothe out-door temin the circuit, and the flame is complete.These resistances are inserted in circuit by a movable contact, theposition of which is determined by a temperature sensitive instrumentoutside the building.

By the application of these two control tems simultaneously, both thetemperature of the boiler and the size of flame will be controlledautomatically in relation to the outside temperature.

In case the flame is extinguished its rekindling cannot be eflected inthe usual automatic way,

unless the resistance is excluded from the motor circuit and for thisreason a temperature responsive switch is placed in the flue andconnested in parallel with the resistances. This thermostat operatedswitch is closed when the flue is cold and open when the flue is hot.

Other features of the invention will, be apparent from the followingdescription and the accompanying drawings.

In the drawings different embodiments of the invention arediagrammatically illustrated.

Fig. 1 shows a system,'in which the temperature of the boiler isregulated in accordance with the outside temperature.

Fig. 2 shows a system in which both the boiler temperature and thesizeof the flame are regulated in accordance with the outside temperature an1 Fig. 3 shows a system similar to Fig. 2.

In Fig. 1 I isthe temperature instrument which is sensitive to theoutside temperature,

in this case a mercury thermometer having contacts at 10 0., --5 0., 00., +5 C. and +10 C. From these contacts lines pass through the wall 2of the .building to contacts 3, I, I, 9 and II, which are crosswiseconnected to the consys- I 4, 5 and 8, 1 and 9, 9 and I and and I21 areconnected. A device i3, controlled by the boiler temperature, has acontact-piece I l, which at definite temperatures, for example at 40 C.,45 0., 50 0., 55 C. and 60 C. respectively connects the contacts 12,iii, 8, and 4 with the contact bar it. In case the outside temperatureis below -10 0., no current will pass through the winding it and thetemperature in the boiler i'l may increase to 65 C. for example, beforethe switch it'd, operated by the thermostat it opens the motor circuitin the known manner. When the outside temperature is '-10 C. thecontact-piece it will connect the contact t with the bar it, the heatercircuit is closed, heat is produced by the winding i6, and thethermostat operates: be-

, fore the'boiler temperature has reached the adjusted temperature of 65C. In the same way, the boiler temperature will be adjusted in desiredrelation to the difl'erent outside temperatures.

In the system shown in Fig; 2, I1 is the boiler provided with thetemperature regulated device l9, which is adapted to receive additionalheat from the winding "5 in the manner described above or is otherwiseinfluenced in relation to r the outside temperature.

The boiler also has another temperature sensitive device i3, which issimilar to that shown in Fig. 1 and operates a contact-piece 20 for theregulation of the number of revolutions oi the motor 22. The combinedsystem operates: as follows:

When the plant is put into operation the plant operates with completeflame, as the motor 22 receives complete voltage'from the supply mainsvit through the-thermostat operated switch ltd and the contact-piece 20.With increasing boiler temperature, the contact-piece 20 moves upwardsalong the contact-bars 2!, until the temperature has increased so muchthat the contact-piece 2i! no longer bridges the bars 2! and the motorcurrent therefor, instead of flowing through the contact-piece 2B flowsthrough the line 23 to the contact-bar '24, the contact-piece 251), theposition of which is determined by the thermostat 28, regulated by theoutside temperature and through the resistance b back to the other sideof the line l8. v a

As shownthe outside temperature is 0 C. and

- the resistance 2: is connected in the motor circuit, but the greaterresistance 0 will be inserted in the-motor circuit at +5 C.-, andconsequently the size 01 the flame will be further reduced, and at 10 C.and lower the size of the flame will 7 be complete.

in the present case is considered as convenient in the plant. 1

Fig. 3 shows'an embodiment of the invention, with which satisfactoryresults have been obtained. The plant controls the maximum boilertemperatures in relation to the outside temperav ture according to thefollowing table:

Outside Boiler temperatemperature ture +6 42 +4 44 +2 46 0 48 2 50 i 526 54 -8 56 -10 58 l2 so This embodiment includes a bimetallic thermostat26a arranged outside the building. The thermostat 26a is provided withconducting portions 25a and 25b separated by insulating material toprovide two contact members.

When the outside temperature is for example 10 C. the relay coil 32awill be energized and in the motor circuit and consequently, the size ofthe flame will be somewhat reduced. Incase the outside temperature is-8, the contact-piece 25a engages the contact 351;, and the relay 38will be energized and the resistance a+b is inserted in the motorcircuit. At higher outdoor temperatures the entire resistance a+b+c willI be inserted in'the motor circuit, and the flame will be reduced to thesmallest size. At the temperature of 12 C. and below the contact-piece25a engages the contact-bar 31, and the relay 38 is energized and theresistanceoi the motor circuit is short circuited.

When putting the plant into operation, the

' motor 22 starts without inserted resistance, and

the flame will be complete, as the motor current flows through theswitch 3Q (thermostat) in the This thermostat 39 is closed when thechimney is cold, but when the chimney becomes hot, the thermostat 39 isopened and the motor current will flow through the resistance corre- Atincreasing boiler temperatures the contact-j piece 28 will reach thecontact bar 21 and progressively connect the bar 21 with'contacts 28,29, 30, it which are arranged in positions corre-.

I spending to theboiler temperatures 0.,

Caand C. and 60 C. respectively. -When as in the present case, theoutside temperature is 0 the contact-piece 20 serves to close thecircuit of the winding l8.

Thereby additional heat will be generated in the thermostat. it when thecontact-piece 20 reaches theflcontactfis, which inthis-case correspondsto the boiler temperature 50'. The sir-1 cuit will be establishedthrough the outside temperature adjusted contact-piece 25a, which isinsulated from'the'contact-piece 25b by the insulating piece 32.:Thereby the maximum boiler temperature will be restricted to 50 0;,which sponding to the outside temperature. The boiler temperatureincreases, whereby the contact-piece 20a moves upwards over the contactscorresponding to the diflferent boiler temperatures. 11' the resistor ais correctly adjusted the contact piece 20a will stop immediately belowthe contact corresponding to ajboiler temperature of 58 C. However, ifthe contact piece 20a engages the contact corresponding to 58 C. therelay 40 will be energized whereby the switch No is actuated v and opensthe motor circuit so that the flame is extinguished. p r The controlsystem shown in Fig. 3 includes a switch its arranged in'serie s circultrelation with respect to the switch lab. The switch |9a is actuated bymeans of a thermostat 16 associated with the boiler. The thermostat i5is of a well known type and designed'to open the switch "a when theboiler temperature reaches 65 C. The switch Isa thus serves to open themotor circuit when the boiler temperature exceeds a predetermined valueand provides emergency control means for extinguishing the flame in theevent that the relay 40 fails to function. The thermostat 1G is adjustedto permit closure of the switch l9a at 38 C. so the motor circuit willbe in condition to be completed. The switch I911 will normally remainclosed between 38 and 65 degrees C. so as to be ineffective during thenormal control range between 42 and 60 degrees C.

After the plant has been shut down the temperature of the flue will bereduced and the switch 39 will thus close. The contactpiece 20a willalso move downwardly upon a reduction of the temperature of the boiler.The relay coil 40 will thus be de-energized and the switch 192) willthen close the motor circuit. The motor will however start at full linevoltage since. the thermostat 39 short circuits the resistors a, b andc. The motor being operated at full speed will provide a complete flameto heat the boiler and the temperature of the flue will rise. Then theswitch 39 opens and resistors will be included in the motor circuit tocontrol the speed of the motor and the size of the flame in accordancewith the position of the thermostat 26a or in relation to thetemperature outside the building.

Whilethe invention has been described with reference to specificdetailed circuit arrangements it will be appreciated that changes may bemade therein. S,uch modifications may be made without departing from thespirit and scope of the invention as set forth in the appended claims. v

I claim:

motor circuitand including said resistor therein a when the outsidetemperature rises above a predetermined value, means responsive to arise in temperature of the boiler for opening said motor circuit, asecond circuit associated with the motor circuit adapted to shunt saidresistor, and means responsive to the absence of heat in said flue forclosing the second circuit whereby the 1. Apparatus for automaticallycontrolling i v the heat output of an oil fired building heating planthaving the oil supplied thereto by a pump and a fan driven by a motorcomprising, an elec-. trical source having one side connected to onemotor is started at full voltage of thesupply.

3. Apparatus for automatically controlling the heat output of an oilfired building heating boiler having the oil supplied thereto by a pumpand a fan driven by a motor comprising, an electrical source having oneside connected to'one terminal of the motor, graduated resistance meansconnected to the other side of the electrical source and adapted to beconnected to the other motor terminal, a thermostat positioned outside'the building, means for establishing circuits from the graduatedresistance means to positions adjacent the thermostat, conducting meansmoved by the thermostat for completing the motor circuit through saidresistance means in accordance with the temperature outside thebuilding, means associated with said thermostat for completing the motorcircuit without including the resistance means when the temperatureoutside the building building having the oil supplied thereto by a pumpand a fan driven by a motor comprising, an electrical source having oneside connected to oneterminal of the motor, resistance means conterminalof the motor, graduated resistance means connected to the other side oftheelectrical source and adapted to be connected to the other motorterminal, a thermostat positioned outside the building, means forestablishing cir cuits from the graduated resistance means to positionsadjacent the thermostat, conducting means moved by the thermostat forcompleting the motor circuit through said resistance means in accordancewith the temperature outside the building, a second circuit associatedwith said source, additional conducting means moved by the thermostatincluded'in the second circuit, movable means interposed in said secondcircuit operably responsive to the temperature of the plant, conductorsextending from positions adjacombination, an electrical supply havingoneside' thereof connected to one, terminal of the motor, at least oneresistor connected to the opposite side of the supply and adapted'to beincluded in a circuit extending to the othermotor terminal, temperatureresponsive means arranged outside of the building, means associated withsaid temnected to the other side of said source adapted to be includedin a circuit extending to the other motor terminal, a thermostatarranged outside the building, means including conducting means 'movedby the thermostat for completing the m0- tor circuit through saidresistance means in accordance with the temperature outside thebuilding, a second circuit associated with 'said source,

additional conducting means moved by the thermostat included in thesecond circuit, movable means associated with said second circuitoperably responsive to the temperature of the plant,

conductors extending from positions adjacent the additional conductingmeans to positions adjacent the movable means, and means responsive tothe completion of said second circuit through one of said conductors foropening said motor circuit. i

5. Apparatus for automatically controlling the heat output of an oilfired heating plant for e. building having the oil supplied thereto by apump and a fan driven by amotor comprising, an electrical source havingone side connectedto one terminal of the motor, resistance meansconnected to the opposite side of said source adapted to be included ina circuit extending to the other motor terminal, a thermostat arrangedoutside the building, means including conducting means moved by thethermostat for completing the motor circuit through saidresistance'means in accordance with the temperature outside thebuildperature responsive means for completing the 7 additionalconducting means moved by the ther completing the motor circuit throughmostat included in the second circuit, movable means associated withsaid second circuit operably responsive to the temperature or the plant,conductors extending from positions adjacent the additional conductingmeans to positions adjacent the movable means, means responsive to thecompletion of said second circuit through one of said conductors foropening said motor circuit, an auxiliary motor circuit for shunting saidresistance means, and means in said aumliary motor circuit responsive toa predetermined low temperature of the plant for closing 'the auxiliarymotor circuit.

6. Apparatus for automatically controlling the heatoutput'of an oilfired heating plant for a building having the. oil supplied thereto by apump and a fan driven by a motor comprising, an

electrical source having one side connected to one terminal of themotor, a resistor connected to the opposite side oi. said source adaptedto be included in a circuit extending to the other motor terminal,athermostat arranged outside the a building, a switch controlled by thethermostat for completing the motor circuit through said resistor whenthe temperature outside the building rises above a predetermined value,a second circuit associated with said source, conducting means moved bythe thermostat included in the second circuit, movable means in saidsecond circuit operably responsive to the temperature of, the plant,conductors extending from posi-' able upon the completion of said secondcircuit through one of said conductors for opening said motor circuit.

7. Apparatusforautomatically controlling the heat output 01' an oilfired heating plant for a pump and a fan driven by a motor comprising,an electrical source having one side connected to one terminal oi themotor, a resistor connected to the opposite side of said source adaptedto be included in a circuit extending to the other motor terminal, athermostat arranged outside the aasaees mostat for completing themotorzcir'cuit through said resistor when the temperature outside thebuilding rises above a predetermined value, a

second circuit associated with said source, addi-' tional conductingmeans moved by thev thermostat included in the second circuit, movablemeans 7 in said second circuit operably responsive-to the temperature ofthe plant, conductors. extending from positions adjacent the additionalconducting means to positions adjacent the movable means, a secondthermostat, a switch operated by the second thermostat for opening saidmotor lcircuit, an electrical heater in said second circuit adjacentsaid second thermostat whereby the heater is energized upon thecompletion of the second circuit.

' 9. Apparatus for automatically controlling the heat output of an oilfired heating plant fora building having the oil supplied thereto by ations'adjacent the conducting means to positions 7 adjacent the movablemeans, and a switch operpump and a fan driven by a motor comprising,

an electrical source having one side connected to one terminal of themotor, a resistor connected to the opposite'side of said source adaptedto be included in a circuit extending to the other motor terminal, a'thermostat arranged outside the building, conducting means moved by thethermostat for completing themotor circuit through said resistor whenthe temperature outside the building rises above a: predetermined value,a-

second circuit associated with said source, additional conducting meansmoved by the thermo stat included in the second circuit, movable meansin said second circuit oper'ably responsive to the temperature of theplant, conductors extending from positions adjacent the additionalconducting means to positions adjacent the movable means, thermalresponsive means responsive building having the oil supplied thereto bya building, means controlled by the thermostat for id reto apredetermined high temperature of the plant 'forgpening the motorcircuit,-and an electric heater energized upon \the completion of thesecond circuit to .supply'heat to said thermal responsive means wherebythe motor circuit is opened at a temperature lower than saidpredetermined high plant temperature.

10. Apparatus for, automatically controlling the heat output of an oiliired heating plant for "a building having the oil supplied thereto by asister when the temperature outside the uilding risesabove apredetermined value, a second circuit associated with said source,conducting means moved by the thermostat included in the second circuit,movable means in said second cirbuilding having the oil supplied theretoby a pump and a tan driven by a motor comprising, an electrical sourcehaving one side connected to one terminal or the motor, a resistorconnected to the opposite side oi said source adapted to be included ina circuit extending to the other motor terminal, a thermostat arrangedoutside the building, conducting means moved by the therpumpv and a fandriven by a motor comprising, an electrical source'having one sideconnected to one terminal of the motor, a resistor connected to theopposite side of said sounce adapted to be included in a circuitextending to the other ,motor terminal, a thermostat arranged outsidethe building, means controlled by the thermostat for completing themotor circuit through said resistor when the temperature outside thebuilding rises above a predetermined value, a second circuit associatedwith said source, conducting means moved by the thermostat included inthe second circuit, movable means in said second circuit operablyresponsivev to the temperature of the plant,.conductors extending frompositions adjacent the conducting means to positions adjacent themovable means, means responsive to the completion or said second circuitthrough'one of said conductors for opening said motor circuit, a

,flue for said plant, an auxiliary motor circuit adapted to shunt saidresistor, and means responsive to the absence or heat in said iiue forclosing the auxiliary motor circuit.

' l l PE'I'I'ER HARTMANN-RIIS.

